The primary aim of the proposed research is to investigate the hypothesis that language comprehension involves the use and manipulation of perceptual symbols. Perceptual symbols are representations stored in long-term memory, which are the result of the perceptual experience of an event or object. Perceptual symbols capture those aspects of an event or object that were in focused attention. Perceptual symbols can be activated, for instance, by verbal stimuli, thus recreating the perceptual experience in a perceptual simulation. Language can be thought of as a set of cues to the comprehender on how to run a perceptual simulation. This view can be contrasted with the amodal propositional view, which is currently prevalent in cognitive science. On this view, objects and events are represented by networks of abstract propositions constructed from the verbal input, which bear no analog relation to their referents. There is as yet no systematic body of empirical evidence regarding these competing hypotheses about the building blocks of cognition. Four sets of experiments are proposed that are intended as a first concerted attempt to fill this gap. The first set examines whether comprehenders mentally represent the orientation of objects when this is implied by the linguistic input. The second set examines whether comprehenders mentally represent the shape of objects or animals when this is implied by the verbal input. The third set examines whether language processing can result in representational motion. Finally, the fourth set examines whether the processing of words denoting parts of larger objects (e.g., "lid," "elbow") activate perceptual representations of the larger object. The proposed research has theoretical and practical significance. In the theoretical domain, it addresses in a novel way the relation between mental representations and their referents in the context of language comprehension. As such, it is intended to yield new insights into the building blocks of cognition and into the relation between perception and cognition. In the practical domain, the proposed experiments could lead to the development of novel diagnostic tests to assess comprehension skill in various groups, including children, children with reading disability, older adults, older adults with Alzheimer's disease, and individuals with brain damage.